I have also had this happen a few times with my HW v2.3, FW 2.1.4 OS. Pings start getting flakey, and most API calls timeout or fail, but some small percentage of the traffic still gets through though. It doesn’t appear to be related to the TP-Link wireless bridge, as rebooting the OS (via API call) immediately resolves the issue. I have attached a graph from my Cacti ping monitor for the OS before, during and after the issue appears.
